In a radial compressor (see FIG. 1), the fluid to be compressed exits an impeller, rotating around an axis, in the radial direction with a significant velocity component in the circumferential direction (swirl). The following static aerodynamically effective components in the flow direction have the task of converting the kinetic energy introduced in the impeller into pressure. In the case of a multistage single-shaft compressor, as known from JP000244516 for example, the fluid also has to be conducted toward the following impeller. Furthermore, the swirl is to be extracted from the flow so that flow onto the following impeller is swirl free as far as possible. This task is solved by means of a so-called backfeed stage, comprising a first section which conducts the process fluid radially outward, a second section which corresponds basically to a 180° bend, and a third section for conducting the process fluid radially inward for entry into the impeller following downstream. The third section also involves a deflection of the processing fluid from the radially inwardly directed flow into the axial direction toward the impeller inlet of the downstream impeller. The backfeed blading can in this case consist of individual blades arranged in a row in the circumferential direction, as is known from JP 11173299-A.
From JP2015094293(A) it is already known to arrange second downstream guide vanes closer to the pressure side of first upstream guide vanes.
The arrangement which is known from the prior art is not very compact—therefore comparatively space-consuming—and the throughflow is comparatively loss-impaired.